Clinical ultrasound diagnostic equipment is well known in the medical arts for viewing internal human organs. For example, opthamologists and radiologists often require images of the eye for investigating eye maladies and for making volumetric measurements. In diagnosing prostate cancer, a diagnostician uses transrectal ultrasound (TRUS) to identify whether lesions are present, and determines the location, size and extent of the lesions. However, such prior art ultrasound devices produce only 2-D images whereas the anatomies under investigation are three-dimensional. Hence, the diagnostician must interpret multiple images and integrate them in his or her mind to develop a 3-D impression of the anatomy and pathology under examination. This practice, although routine, is often time consuming and inefficient, and creates the potential for non-optimal diagnosis, and non-optimal staging of disease.
Also, the ultrasound image in prior art 2-D imagers represents a single plane approximately 1 mm thick and at an arbitrary angle in the patient's body. Thus, it is generally difficult to localize the image plane in the organ, and very difficult to reproduce a particular image location at some later time.
Prior art ultrasound imaging systems typically comprise a probe for transmitting ultrasound signals into the human body and receiving reflected ultrasound signals therefrom, and a conventional clinical ultrasound machine for receiving and processing analog ultrasound signals from the probe for generating multiple images of the organ.
A number of patents have been issued relating to prior art probes with internal mechanical sensors. Examples of these systems are disclosed in the following U.S. Pat. Nos.: 5,159,931 (Pini); 5,152,294 (Mochizuki et al); 4,819,650 (Goldstein); 4,841,979 (Dow et al) and 4,934,370 (Campbell).
Prior art systems are also known to use encoders for determining the position of the sensors and transmitting that information to a controlling computer. Examples of such systems are disclosed in the following U.S. Pat. Nos.: 5,159,931 (Pini); 5,152,294 (Mochizuki et al); 4,932,414 (Coleman et al); 4,271,706 (Ledley); 4,341,120 (Anderson); 5,078,145 (Furuhata); 5,036,855 (Fry et al); 4,858,613 (Fry et al) and 4,955,365 (Fry et al).
Other patents have issued which provide general background information on the subject of clinical ultrasound imaging systems. U.S. Pat. No. 5,081,993 (Kithey et al), discloses an intravascular probe for insertion into blood vessels. It incorporates an array of crystals surrounding a tube and generates a cross-sectional view. U.S. Pat. No. 4,747,411 (Ledley) discloses a 3-D imaging system which requires the use of stereo eyeglasses. U.S. Pat. No. 4,899,318 (Schlumberger et al) and U.S. Pat. No. 4,028,934 (Sollish) relate to specific methods of stereoscopic 3-D visualization of objects. U.S. Pat. No. 3,555,888 discloses a probe having a single crystal and a mechanical means for moving the single crystal. U.S. Pat. No. 4,564,018 (Hutchison et al) discloses an ultrasonic diagnostic scanner for producing peak signals and count signals responsive generation of the peak signals for identifying a perceptible eye parameter. U.S. Pat. Nos. 4,594,662; 4,562,540 and 4,598,366 relate to 3-D holography. U.S. Pat. No. 4,866,614 (Tam) teaches the use of a plurality of stationary ultrasound beams which are generated on the basis of multiple transducers. PCT application number PCT/EP92/00410 (Technomed International) discloses a treatment probe inserted into the urethra and means for rotating and moving the probe up and down on a stand.
U.S. Pat. No. 4,932,414 (Coleman) is of interest for disclosing an extension of kidney stone acoustic shattering techniques, applied to the eye. In order to see what a surgeon is doing, an ultrasound imaging probe is provided for sweeping out a volume of the eye resulting in a 3-D impression when the volume is swept quickly enough. However, the Colemen Patent does not disclose any means for reconstruction of the 3-D image from the multiplicity of generated 2-D images. Furthermore, the system of Coleman et al teaches the use of an encoder for determining the position of the probe.